How do I get rid of white stuff on citrus trees?

Spray with a combo of water, some chil I powder and dishwashing soap.

Those are white flies, if there’s a sooty substance too. Maybe mold, of which I can’t recall the species now.

What are the things you’ve tried?

Having lived in So Cal and having fruit trees that had this, I had to use Sevin in a hose sprayer applicator.

powdery mildew, a type of fungus that causes a white, powdery substance to appear on branches. Some insect pests, such as citrus snow scale and mealy bugs, may resemble powdery mildew when massed together. Treatment

Powdery mildew can be treated with regular applications of a fungicide such as neem oil, sulfur or triforine. Baking soda, mixed with a lightweight horticultural oil, may also be successful. According to Colorado State University, fungicides are most effective when used along with cultural care methods such as removing and destroying infected growth and debris. Mildew-covered plant debris should not be composted, as the fungus will continue to live in the compost bin.

Other Causes

Citrus snow scale can form dense colonies on the branches and trunks of an orange tree, appearing as snowy white patches. Eventually they move onto the leaves and fruit of the tree. Other symptoms of citrus snow scale may include reduced fruit production, leaf drop, branch die-back and cracked bark. Mealy bugs also appear in cottony white masses. Mealy bugs are seen along with a sticky residue known as honeydew. Mealy bugs may be controlled with predatory insects. According to the University of Florida, citrus snow scale has few predatory insects and is better controlled with a scalicide.

Prevention

Help prevent disease and insect problems by following basic orange tree care guidelines. Orange trees do best in bright, full sun with well-draining, moist soil. Oranges grown in shade are much more likely to fall prey to fungal attacks, and in a weakened state, will more likely attract pests as well. Do not water orange trees from overhead, as the increase in humidity, coupled with wet plant tissue, invites fungal disease. Remove weeds, which can compete with the tree for nutrients while also hiding pests.

I used a spray of 20 percent milk and 8o

percent tap water. Keep the spray in the fridge but its ok if it sours. Spray daiy until the mold is gone

Look up scrubbing bubbles. .It cleans plants and is safe.. not sure where I read this...

First you must determine precisely what the issue is. Here are links to the most likely causes. Once you know what it is, google how to DIY take care of it.

https://homeguides.sfgate.com/white-stuff-citrus-trees-56321.html

https://homeguides.sfgate.com/white-powder-orange-trees-54314.html